NEW YORK  The financial turmoil rippling across the globe will set back efforts to fight climate change, drying up capital that could help poorer countries upgrade to clean energy technology, the U.N. climate chief said Thursday.

In an Associated Press interview, de Boer said a pledge of northern investment in developing countries, for "green" economic growth and for adapting to droughts, floods and other impacts of warming, would be essential to get poorer nations to sign onto a new global climate agreement.

Ongoing negotiations aim to produce such an agreement at a U.N. climate conference in Copenhagen in late 2009. Richer industrialized nations want China, India and other big Third World emitters of greenhouse gases, countries exempt under the current Kyoto Protocol, to contribute in some way to a new regime of reducing emissions.

But the credit crisis gripping the international economy changes the outlook, de Boer said.

"I think that the financial crisis is going to make it more difficult for industrialized countries to make public resources available for cooperation with developing countries," he told the AP.

"Many industrialized countries at the moment are propping up their financial sector and they're borrowing money to do it, which means to my mind that there's going to be a constraint on the capital market, and that potentially can impact the negotiations."

De Boer was in New York to confer with U.N. Secretary-General Ban Ki-moon and to take part in a public debate with Columbia University's Jeffrey Sachs, a leading development economist, on whether the world should pursue carbon taxes to discourage the burning of fossil fuels -- source of much atmospheric warming -- rather than the "carbon trading" system overseen by de Boer's U.N. agency.

In carbon trading, under the Kyoto Protocol, industries subject to emissions caps are allotted or sold emission allowances that they then can buy and sell among one another.

But such long-running economic arguments -- the consensus among four debaters was that many devices will be needed -- are increasingly overshadowed by scientific news that experts say points up the need for more urgent, sweeping action.

It was reported last month that worldwide man-made emissions of carbon dioxide -- the leading greenhouse gas -- leaped by an unexpected 3 percent in 2007. And de Boer noted that U.N. scientists who last year forecast a need for 50 percent reductions in global emissions by 2050 are now saying 60-to-80 percent cuts will be necessary to avoid the worst of climate change.

The U.N. climate chief finds encouragement in the U.S., however, where both major presidential candidates, Sens. John McCain and Barack Obama, favor a cap-and-trade system, after eight years in which the Bush administration rejected the Kyoto Protocol and mandatory emissions cuts.

De Boer said he hoped the next president could show his commitment personally at the annual U.N. climate conference in early December, in Poznan, Poland.

"If the president-elect or vice president or a bipartisan delegation of some kind could come to Poznan with the message that the U.S. takes this issue seriously, that would be a very strong signal of encouragement," he said.

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